V engines having two cylinder banks typically use cylinder heads of different configurations, typically a mirror image of each other. In particular, the camshaft of each cylinder bank projects axially beyond the timing belt end of the cylinder head, but extends short of the opposite end of the cylinder head.
The need for cylinder heads of two different configurations in manufacturing V engines obviously adds to the manufacturing cost. Therefore, it has been proposed to use common cylinder heads for the two cylinder banks of a V engine. See JPS62-69051U, for instance. In this prior art, two different adapters are attached to the timing belt ends of the respective cylinder heads so that the timing pulleys attached to the respective camshafts may be positioned on a same plane, and the opposite ends of the cylinder heads are closed by lid plates.
However, this prior art is only concerned with the arrangements for supporting the camshafts, and no considerations are given to the arrangement of the oil passages. As the modern automotive engines are provided with highly complex oil passage systems, for improved lubrication of the engines and the use of engine oil as a working fluid for various actuating purposes. Therefore, there is a need for an improved V engine which uses common cylinder heads and permits a favorable arrangement of oil passages.